Universität zu Köln

Yu, Qingfen (2017). Nanoparticle-membrane interactions. PhD thesis, Universität zu Köln.

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Abstract

Biological membranes are fluid thin films composed of lipids, proteins and sugars. Nanoparticles are one specific nano-scale cargo that can be engineered with controlled structure, composition, and physicochemical surface properties. However, the mechanical mechanisms for nanoparticle-membrane interactions are still debated. For the interaction of nanoparticles with non-spherical vesicles, the roles of particle size, vesicle size, vesicle shape, and membrane spontaneous curvature on both nanoparticle wrapping and vesicle shape are studied. For non-spherical vesicle shapes, such as stomatocytes, oblates, and prolates, not only the local curvature at the point where the particle attaches but also the deformation energy of the free membrane is important. For fixed vesicle volume and membrane area, complex wrapping behavior is found, where particle wrapping transitions and vesicle shape transitions can be coupled. Furthermore, partial-wrapped membrane-bound particles impose boundary conditions for the free membrane that stabilize oblates and stomatocytes for particle entry, and prolates and stomatocytes for particle exit. If the vesicle volume can vary upon nanoparticle wrapping, the presence of solute inside the vesicle gives rise to a compression energy contribution to the vesicle deformation energy. The deformation-induced osmotic pressure difference stabilizes partial-wrapped states for both nanoparticles entering and exiting vesicles. For high solute concentrations, the transition between the partial-wrapped and the complete-wrapped state becomes discontinuous. Finally, wrapping of nanoparticles at membrane tubes is investigated. Here, both wrapping transitions and membrane-mediated particle-particle interactions are studied. Contrary to the literature, both mutual attraction and repulsion between nanoparticles are observed. The results presented in the thesis contribute to systematical understanding of membrane wrapping of nanoparticles.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Yu, Qingfen q.yu@fz-juelich.de UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-79489
Date:	23 October 2017
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Physics > Institute for Theoretical Physics
Subjects:	Physics
Uncontrolled Keywords:	Keywords Language nanoparticles, membranes, vesicles, membrane tethers, endocytosis, exocytosis, continuum membrane models, computer simulations English
Date of oral exam:	15 December 2017
Referee:	Name Academic Title Gompper, Gerhard Prof. Dr. Dhont, Jan K. G. Prof. Dr.
Funders:	China Scholarship Council
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/7948